Braking- and damping device, in particular for movable pieces of furniture

ABSTRACT

A braking- and damping device, in particular for movable pieces of furniture, having a fluid-cylinder ( 1 ) in which two pistons ( 2, 5 ) are arranged in linearly displaceable manner. A piston ( 2 ) is displaceable over a piston rod ( 3 ). Arranged between the two pistons ( 2, 5 ) is an elastically deformable sealing member, which, when damping occurs, is deformed by being squeezed between the two pistons ( 2, 5 ) and pressed against the cylinder wall ( 7 ).

[0001] The invention relates to a braking- and damping device, inparticular for movable pieces of furniture, having a fluid-cylinder inwhich two pistons are arranged in linearly displaceable manner, whereina piston is displaceable over a piston rod.

[0002] With modern furniture, braking- and damping devices are beingused increasingly in order to prevent a door of a piece of furniturewhich is slammed shut too forcefully or a drawer which is pushed into afurniture frame with too much force from hitting the end wall of thefurniture frame. The oldest damping devices were formed from simplerubber buffers. More recently, pneumatic and hydraulic braking- anddamping devices have been used.

[0003] In the case of drawers, they are preferably combined with adrawing in device. Also, doors or flaps are in many instances providedwith hinges which have a closure mechanism which are then responsibletogether with the damping device for an optimum course of movement.

[0004] In the case of fluid damping devices, i.e. pneumatic or hydraulicdamping devices with a linearly movable piston it has been seen thatwith high speeds or large volumes the damping effect of the fluid isinsufficient to brake the moving piece of furniture adequately.

[0005] U.S. Pat. No. 4,877,226 therefore proposed a fluid damping devicewith a linearly movable piston which the piston radially expanded duringthe damping operation and pressed against the cylinder wall, so that inaddition to the damping effect caused by the fluid frictional dampingoccurred between the cylinder and piston.

[0006] The aim of the invention is to create a pneumatic or hydraulicbraking- and damping device of the kind mentioned in the introduction,wherein improved sealing between the piston and cylinder wall isachieved, and wherein spring-back during braking by the cushion of air,or cushion of fluid, occurring in the cylinder is avoided.

[0007] The problem of the invention is solved in that arranged betweenthe two pistons is an elastically deformable sealing member, which, whendamping occurs, is deformed by being squeezed between the two pistonsand pressed against the cylinder wall.

[0008] Advantageously, it is provided that the piston which isdisplaceable linearly over a piston rod has an open cavity at the frontface thereof into which the second piston is introduced, wherein thesecond piston is mounted in the first piston in freely displaceablemanner, and, on the outer casing, has an annular projection which isdisposed in front of the first piston, and arranged between the annularprojection and the front face of the first piston is the sealing memberwhich is in the form of a sealing ring.

[0009] Advantageously, it is further provided that provided in thecavity of the first piston are abutments which delimit the path ofdisplacement of the second piston.

[0010] One embodiment of the invention provides for at least one elasticspacer to be provided between the floor of the cavity of the firstpiston and the rear side of the second piston.

[0011] Another embodiment of the invention provides for the sealingmember to be designed as a cylindrical solid body made from a rubberelastic material or as a cylindrical bellows. The cylindrical shapeexists therein in the unloaded state. When loaded, the sealing memberbecomes compressed and deformed.

[0012] There will now follow a description of various embodiments of theinvention with the aid of the accompanying drawings, wherein:

[0013]FIG. 1 shows a longitudinal section through the piston and thecylinder of a braking- and damping device according to the invention, inthe ready position,

[0014]FIG. 2 and FIG. 3 each shows a longitudinal section through thepiston and the cylinder of FIG. 1, wherein the pistons are shown duringthe braking path, and

[0015]FIG. 4 shows a longitudinal section through the pistons and thecylinder, wherein the pistons are shown at the end of the braking path,

[0016]FIG. 5 shows a longitudinal section through the pistons and thecylinder, wherein the pistons are shown in the restoring phase,

[0017]FIG. 6 shows a longitudinal section through a cylinder piston unitaccording to another embodiment of the invention,

[0018]FIG. 7 shows section A of FIG. 6, wherein the piston is shown inthe damping position,

[0019]FIG. 8 shows section A of FIG. 6, wherein another embodiment of apiston is shown in the damping position,

[0020]FIG. 9 shows the same cut-out section as FIG. 7, wherein thepiston is shown in the ready-, or restoring, position,

[0021]FIG. 10 shows the same cut-out section as FIG. 8, wherein thepiston is shown, once again, in the ready-, or restoring, position.

[0022] The braking- and damping device according to the invention has acylinder 1 in which a piston 2 is arranged in linearly displaceablemaimer. Therein, the piston 2 is provided with a piston rod 3. Thepiston rod 3 forms a plunger which is preferably acted upon by themovable piece of furniture. By way of example, the cylinder 1 is securedto the side wall or a piece of furniture, or to the top or floor of apiece of furniture, and in such a way that a closed door or end panel ofa closed drawer abuts on the head 4 of the piston rod 3.

[0023] In the embodiment according to FIGS. 1 to 5, the piston 2 isprovided with an open cavity 10 in the front face thereof, into whichcavity a second piston 5 is inserted.

[0024] The first piston 2 has an annular projection 8 on the insidewhich acts as an abutment for delimiting the path of the second piston5. During the relative rearward movement of the piston 5, the abutmentis formed by the floor 11 of the cavity 10 in the piston 2.

[0025] The piston 5 is likewise provided with an annular projection 16which forms a counter-abutment, and, when the piston 5 is disposed inthe frontmost position in relation to the piston 2, rests upon theannular projection 8.

[0026] The piston 5 may be made of a plastics material, for example, andformed on the rear side of the piston 5 is at least one spacer 20 whichbears in at least one recess 21 in the floor of the cavity 10 in thepiston 2.

[0027] The front face 9 of the first piston 2 is inclined and extendsfrom the centre of the pistons 2, 5, inclinedly to the rear, viewed withrespect to the cylinder wall 7.

[0028] The ready position of the braking- and damping device is shown inFIG. 1. The pistons 2, 5 are disposed at the upper end of the cylinder1.

[0029] The term, “upper” is used here in relation to the drawings.

[0030] The piston 5 is held by the spacer 20 at a spacing from the floor11 of the cavity 10, and the sealing member which is in the form of asealing ring 6 is disposed with a certain clearance between the frontface 9 of the piston 2 and an annular projection 22 of the piston 5. Ifa door of a piece of furniture or an end panel of a drawer strikes thehead 4 of the piston rod 3, the pistons 2, 5 are pushed down in thecylinder, and, as can be seen from FIG. 2, the spacer 20 is pushed down.

[0031] When this happens, the sealing ring 6 is squeezed, deformed incross-section, and pressed against the inner wall 7 of the cylinder 1.

[0032] The cylinder wall 7 is provided with axially extending ribs 15which permit the passage of air when the piston 2 is disposed in thefrontmost position.

[0033] In so doing, the pistons 2, 5 are pressed apart by the spacer 20(see FIG. 4).

[0034] The piston 5 is provided with a skirt 19 consisting of arubber-like or elastomer material, which preferably skims the inner wall7 of the cylinder 2.

[0035] On the rear side of the piston 2, the cylinder 1 has air intakeopenings 23, and on the front side a return valve 12 with a dischargeopening 13.

[0036] During damping, air is only able to escape slowly through therelatively small opening 13.

[0037] When the pistons 2, 5 are withdrawn by the spring 14, i.e. arereturned to the ready position, the return valve 12 opens and air, oranother fluid, is able to flow unhindered into the cylinder 1.

[0038] In the embodiment shown, the second piston 5 is also providedwith a cavity 25 which is open towards the front.

[0039] In the embodiments shown in FIGS. 6 to 10, an elasticallydeformable sealing member is also arranged between the pistons 2, 5.

[0040] In the embodiment according to FIGS. 7 and 9, the elasticallydeformable sealing member is formed by a solid body 18 consisting ofrubber-elastic material. This solid body 18 has projections 27 by meansof which it is anchored in recesses 26 in the piston 2.

[0041] During the damping operation, i.e. when the piston 2 is beingpressed into the cylinder 1 over the piston rod 3, the solid body 18, asshown in FIG. 7, is compressed between the piston 2 and the piston 5 andpressed against the cylinder wall 7, whereby in addition to the dampingcaused by the fluid damping caused by friction takes place.

[0042] The piston 2 is provided with a seal 30 which bears against thecylinder wall 7. As a result, the resistance to fluid in the cylinder 1is increased.

[0043] In the embodiment according to FIGS. 8 and 10, a bellows 17 isprovided instead of a solid body 18.

[0044] The bellows 17 has angled edges 28 by means of which it isanchored in slots 29 in the pistons 2, 5.

[0045] In the embodiment shown in FIGS. 6, 8 and 10, a compressionspring 31 is provided between the pistons 2, 5 which pushes the pistons2, 5 apart again after damping has occurred.

[0046] The cavity 32 surrounded by the bellows 17 can contain ahydraulic fluid, e.g. oil.

[0047] The outer side of the bellows 17 is provided with annular ribs 24which improve adhesion of the bellows 27 to the cylinder wall 7.

[0048] During the damping process, the pistons 2, 5 are compressed, asshown in FIG. 10, and the bellows 17 is pressed with greater intensityagainst the cylinder wall 7, giving rise to the effect of additionaldamping caused by fiction.

[0049] The damping device according to the invention is preferablydesigned as a pneumatic damping device, e.g. a damping device. However,it could also be implemented in the form of a hydraulic damping device.

1. A braking- and damping device having a fluid-cylinder in which twopistons are arranged in linearly displaceable manner, wherein a pistonis displaceable over a piston rod, wherein arranged between the twopistons is an elastically deformable sealing member, which, when dampingoccurs, is deformed by being squeezed between the two pistons (2, 5) andpressed against the cylinder wall (7).
 2. A braking- and damping deviceaccording to claim 1, wherein the piston which is displaceable linearlyover a piston rod has an open cavity at the front face thereof intowhich the second piston is introduced, wherein the second piston (5) ismounted in the first piston (2) in freely displaceable maimer, and, onthe outer casing, has an annular projection (22) which is disposed infront of the first piston (2), and arranged between the annularprojection (22) and the front face (9) of the first piston (2) is thesealing member which is in the form of a sealing ring (6).
 3. A braking-and damping device according to claim 2, wherein the front face (9) ofthe first piston (2) is inclined rearwardly from the second piston (5)towards the cylinder wall (7) of the cylinder (1).
 4. A braking- anddamping device according to claim 2, wherein provided in the cavity (10)of the first piston (2) are abutments which delimit the path ofdisplacement of the second piston (5).
 5. A braking- and damping deviceaccording to claim 2, wherein the second piston (5) is provided with anannular skirt (19).
 6. A braking- and damping device according to claim5, wherein the skirt (19) consists of a rubber elastic material.
 7. Abraking- and damping device according to claim 5, wherein the skirt (19)skims over the cylinder wall (7) of the cylinder (1).
 8. A braking- anddamping device according to claim 2, wherein provided between the floor(11) of the cavity (10) of the first piston (2) and the rear side of thesecond piston (5) is at least one elastic spacer (20).
 9. A braking- anddamping device according to claim 8, wherein the second piston (5) ismade of plastics material, and the, at least one, spacer (20) is formedon the rear side of the second piston (5).
 10. A braking- and dampingdevice according to claim 8, wherein provided in the floor (11) of thecavity (10) of the first piston (2) is at least one recess (21) for the,at least one, spacer (20).
 11. A braking- and damping device accordingto claim 1, wherein provided on the cylinder wall (7) are axiallyextending grooves (15) which permit the passage of the pneumatic mediumwhen the pistons (2, 5) are disposed in their front end position.
 12. Abraking- and damping device according to claim 1, wherein the piston (5)which is oppositely disposed to the piston (2) with piston rod (3) isprovided with a seal which seals the cylinder wall (7) of the cylinder(1).
 13. A braking- and damping device according to claim 1, wherein thesealing member in the form of a solid body (18) is manufactured from arubber elastic material which connects the two pistons (2, 5).
 14. Abraking- and damping device according to claim 1, characterised in hatthe elastically deformable sealing member is designed as a cylindricalbellows (17).
 15. A braking- and damping device according to claim 14,wherein the cylindrical bellows (17) has a plurality of peripherallyextending ribs (24) which lie sealingly against the cylinder wall (7).16. A braking- and damping device according to claim 14, wherein thebellows (17) contains a hydraulic fluid.
 17. A braking- and dampingdevice according to claim 1, wherein inserted between the two pistons(2, 5) is a compression spring (31).
 18. A braking- and damping deviceaccording to claim 14, wherein the bellows (17) is anchored with apositive fit in the pistons (2, 5).
 19. A braking- and damping deviceaccording to claim 13, wherein the pistons (2, 5) have recesses (26) intheir front faces, into which recesses projections (27) of thedeformable sealing member are received.
 20. A braking- and dampingdevice according to claim 11, wherein the pneumatic medium is air.
 21. Abraking- and damping device according to claim 1 for movable pieces offurniture.